Immune checkpoint blockade has demonstrated unprecedented success in the past few years as cancer treatment. Often antibodies are used to block immune inhibitory pathways, such as the cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed death 1 (PD-1) pathways. While therapies targeting those two pathways have shown success in treating several cancer types, anti-CTLA-4 and anti-PD-1 therapies have a response rate of 10 to 60% of treated patients, depending on cancer type, and have not yet shown the ability to exceed a response rate of 60%, even when used in combination (Kyvistborg et al., Enhancing responses to cancer immunotherapy; Science. 2018 Feb. 2; 359(6375):516-517). Additionally, a large number of cancer types are refractory to these therapies. As part of efforts to improve existing immunotherapies in the clinic, the field has started to focus on the role of abnormalities in interferon signaling and upregulation of alternative checkpoints as potential causes for the limitation of current therapies. One such potential alternate checkpoint is T-cell immunoglobulin mucin-3 (Tim-3)/Galectin-9 (e.g., reviewed in Yang and Hung; The role of T-cell immunoglobulin mucin-3 and its ligand galectin-9 in antitumor immunity and cancer immunotherapy; Cancer biology and cancer treatment; October 2017, Vol. 60 No. 10: 1058-1064, and references therein).
Galectin-9 is a tandem-repeat lectin consisting of two carbohydrate recognition domains (CRDs) and was discovered and described for the first time in 1997 in patients suffering from Hodgkin's lymphoma (HL) (Tureci et al., J. Biol. Chem. 1997, 272, 6416-6422). Three isoforms exist, and can be located within the cell or extracellularly. Elevated Galectin-9 levels have been in observed a wide range of cancers, including melanoma, Hodgkin's lymphoma, hepatocellular, pancreatic, gastric, colon and clear cell renal cell cancers (Wdowiak et al. Int. J. Mol. Sci. 2018, 19, 210). In renal cancer, patients with high Galectin-9 expression showed more advanced progression of the disease with larger tumor size and necrosis (Kawashima et al.; BJU Int. 2014; 113:320-332). In melanoma—a cancer considered as one of the most lethal cancers due to its aggressive metastasis and resistance to therapy—Galectin-9 was expressed in 57% of tumors and was significantly increased in the plasma of patients with advanced melanoma compared to healthy controls (Enninga et al., Melanoma Res. 2016 October; 26(5): 429-441). A number of studies have shown utility for Gal-9 as a prognostic marker, and more recently as a potential new drug target (Enninga et al., 2016; Kawashima et al. BJU Int 2014; 113: 320-332; Kageshita et al., Int J Cancer. 2002 Jun. 20; 99(6):809-16, and references therein). Galectin-9 has been described to play an important role in in a number of cellular processes such as adhesion, cancer cell aggregation, apoptosis, and chemotaxis. Recent studies have shown a role for Galectin-9 in immune modulation in support of the tumor, e.g., through negative regulation of Th1 type responses, Th2 polarization and polarization of macrophages to the M2 phenotype. This work also includes studies that have shown that Galectin-9 participates in direct inactivation of T cells through interactions with the T-cell immunoglobulin and mucin protein 3 (TIM-3) receptor (Dardalhon et al., J Immunol., 2010, 185, 1383-1392; Sanchez-Fueyo et al., Nat Immunol., 2003, 4, 1093-1101). Galectin-9 has also been found to play a role in polarizing T cell differentiation into tumor suppressive phenotypes), as well as promoting tolerogenic macrophage programming and adaptive immune suppression (Daley et al., Nat Med., 2017, 23, 556-567). In mouse models of pancreatic ductal adenocarcinoma (PDA), blockade of the checkpoint interaction between Galectin-9 and the receptor Dectin-1 found on innate immune cells in the tumor microenvironment (TME) has been shown to increase anti-tumor immune responses in the TME and to slow tumor progression (Daley et al., Nat Med., 2017, 23, 556-567). Galectin-9 also has been found to bind to CD206, a surface marker of M2 type macrophages, resulting in a reduced secretion of CVL22 (MDC), a macrophage derived chemokine which has been associated with longer survival and lower recurrence risk in lung cancer (Enninga et al, J Pathol. 2018 August; 245(4):468-477).
Accordingly, modulating the activity of Galectin-9 and/or one or more of its receptors may provide a novel cancer therapy approach, alone or in combination with existing therapies. Described herein are novel human antibodies which bind to human Galectin-9 and their therapeutic use in the treatment of cancer.